The prevalence and shedding of porcine epidemic diarrhea virus in intensive swine farms of China from 2022 to 2023

Porcine epidemic diarrhea has emerged as a significant threat to the global swine industry. The shedding and exposure status of porcine epidemic diarrhea virus (PEDV) in intensive farms is not completely understood. In this study, a total of 56,598 clinical samples collected from 256 intensive pig farms in 20 provinces in China from 2022 to 2023, were evaluated for PEDV using quantitative real-time PCR. The overall PEDV prevalence was 11.78 % and 28.45 % at the sample and farm levels, respectively, which are relatively high in Northern China and the fourth and first quarter of the year. The PEDV-positive rates and viral loads in suckling piglet herds were higher than those in growing-finishing pigs and multiparous sows. Meanwhile, 15.61 % of pig pens, 9.51 % of corridors, 9.4 % of office areas, 9.23 % of production personnel, and 8.33 % of pig cart driver samples were positive for PEDV, indicating potential biosafety gaps in intensive pig farms. In addition, 93.41 % of inguinal lymph node tissue samples contained viral nucleic acids, revealing a possible persistent infection of PEDV in pig herds. Our study presents the first report of the large-scale detection of PEDV in intensive pig farms, which constitutes indirect evidence of virus circulation in pig herds. This study provides valuable data for preventing and controlling PEDV infection in the future.